Help! Strange White Growth on Chicken's Back

Today I was sitting with my chickens and one of them ruffled her feathers. When they do this I'll peak in to check if anything is going on with their skin, and sure enough I saw what looked like a larvae attached to her back. Upon further inspection, I tugged on it and it seems like a hard growth that used to have feathers in it at some point. I'm not ruling out that its a parasite, but I'm hesitant to do anything else until I have more information. I should add that she has been low on calcium lately and we have been giving her calcium supplements that our vet gave us.

Has anyone seen this before? A picture of the growth thing is below.

1) What type of bird , age and weight
Buff Orpington, 4 years old, around 6.5lbs

2) What is the behavior, exactly.Some sort of skin problem.

3) How long has the bird been exhibiting symptoms?She has been weaker lately and laying soft eggs so we've been feeding calcium supplements.

4) Are other birds exhibiting the same symptoms?
No, we did get some new chicks recently though and they seem healthy.

5) Is there any bleeding, injury, broken bones or other sign of trauma.
No

6) What happened, if anything that you know of, that may have caused the situation.Not sure

7) What has the bird been eating and drinking, if at all.
She is eating and drinking and has been free-ranging more lately.

8) How does the poop look? Normal? Bloody? Runny? etc.She has runny poop. I figured this had to do with her being weaker for the calcium shortage. It has become less runny as we give her calcium supplements.

9) What has been the treatment you have administered so far?None

10 ) What is your intent as far as treatment? For example, do you want to treat completely yourself, or do you need help in stabilizing the bird til you can get to a vet?
I am willing to take her to the vet when they open tomorrow, although I would like to treat myself if possible.

11) If you have a picture of the wound or condition, please post it. It may help.

12) Describe the housing/bedding in use
We use a wood bedding (aspen bedding from Petco) that we rotate out once or twice a month.